Thrust Areas Ecosystem Water Institute Classification Level
Water, Land Use and Ecosystems Water and Climate Water and Society Water Resources Sustainability Springs Wetlands Watersheds Aquifers Lakes Coastal Zone  Water Institute Classification 1  Water Institute Classification 2  Water Institute Classification 3  Water Institute Classification 4

Reversals of karst springs: Implications for water budgets, water quality, and speleogensis
Goals and Objectives
Reversal of springs during river flooding (e.g., formation of estavelles) are likely to carry organic carbon to oligotrophic environments where it will be remineralized, changing concentrations of nutrients and terminal electron acceptors such as dissolved oxygen (DO), NO3, and Fe and Mn oxides, and increase pCO2. Elevated pCO2 should drive dissolution at the discharge point rather than at sinking streams. Reversals will be controlled by head gradients between the spring, conduits, groundwater, and rivers, but this simplistic view is complicated by antecedent conditions, the rates of diffuse versus allogenic recharge, hydraulic properties of the aquifer, and aquifer confinement. These potential effects of spring reversals lead to questions addressed here including: (1) What are the relationships between hydraulic head in the aquifer, discharge, diffuse recharge, and aquifer confinement? (2) At what rate is backflooding water returned to the surface? (3) What are the primary solid-fluid reactions controlling backflooded water compositions? These questions will be addressed at four springs (Madison Blue, Troy, Peacock, and Fanning) along the Suwannee River in north-central Florida, all of which experience frequent reversals. Madison Blue, Troy and Fanning springs are sites of on-going monitoring programs that have generated much legacy data about flow and chemistry, which will supplement new data collected as part of this project. Samples will be collected at low frequency during base flow to observe background chemical compositions and at high resolution during a reversal event to construct flood chemographs. Specific conductivity, temperature, DO, and pH will be monitored with reliable off the shelf logging instruments. Data collection and analyses will include estimates of reversal magnitudes using available and new discharge data. Sr isotope ratios and age of water (3H/3He ratios and CFC concentrations) will be used to separate fractions of flood water and groundwater. Major element concentrations will be used to assess saturation states of the water. Measurements of DO, NO3, NH4, Fe2+, Fe3+, Mn, sulfate, sulfide, dissolved inorganic and organic carbon concentrations, and ?Ô13CDICvalues will be used to estimate the magnitude of organic matter remineralization. Data modeling will include MODFLOW to simulate flow and PHREEQC to estimate redox and saturation states.
Available Outputs

Title: Dissolution in a variable confined carbonate platform: effects of allogenic runoff, hydraulic damming of groundwater inputs, and surface-groundwater exchange at the basin scale. Earth Surface Processes and Landforms, Vol. 38, Issue 14, pgs. 1700-1713. 2013
Authors: Gulley, J. D., J. B. Martin, P. Spellman, P. J. Moore, E. J. Screaton

Title: Formation of phreatic caves in an eogenetic karst aquifer by CO2 enrichment at lower water tables and subsequent flooding by sea level rise. Earth Surface Processes and Landforms, Vol. 38, Issue 11, pgs. 1210-1224, 2013.
Authors: Gulley, J. D., J. B. Martin, P. J. Moore, J. Murphy

Title: Heterogeneous distributions of CO2 may be more important for dissolution and karstification in coastal eogenetic limestone than mixing dissolution, Earth Surface Processes and Landforms.
Authors: Gulley, J., J. B. Martin, P. J. Moore, A. Brown, P. D. Spellman, J. Ezell

Title: Influence of partial confinement and Holocene river formation on groundwater flow and dissolution in the Florida carbonate platform. Hydrological Processes, Vol. 28, Issue 3, pgs. 705-717.
Authors: Gulley, J. D., J. B. Martin, P. Spellman, P. J. Moore, E. J. Screaton

Title: Insights on surface water-groundwater exchange in the upper Floridan aquifer, north-central Florida (USA) from streamflow data and numerical modeling. Hydrogeology Journal. 2014. 1-13.
Authors: Sutton, J., E. J. Screaton, and J. B. Martin

Title: Presentation: Characteristics and effects of flow reversals at Madison Blue and Peacock Springs (FL) during river flooding
Authors: Martin, J.B., J. Gulley, E.J. Screaton

Title: River reversals in karst springs: a model for cave enlargement in eogenetic karst aquifers. Geologic Society of America Bulletin. 123(3-4): 457-467.
Authors: Gulley, J., Martin, J., Screaton, E., Moore, P.
Project Lead
Martin, Jonathan Bowman
Project Participants
Martin, Jonathan Bowman
Additional Participants
Jason Gulley
P.J. Moore
Elizabeth Screaton
Level 2: WI Assisted Project
Water, Land Use and Ecosystems
Grant Award Dates
8/1/2009 to 9/30/2013